Dan mentioned that he was a former second base baseball player for the Seattle Mariners until he blew out his knee sliding home.
Victor was the first parent to appear in the series and has appeared in each season except for the second season. He has appeared in 14 episodes, which is the same amount as Penny Halliwell, but 5 more than Patty Halliwell.
Billie is neither shown nor mentioned having a familiar like a witch normally should.
The destruction of the dollhouse in Repo Manor foreshadows the events of Kill Billie Vol. 2 when the Manor explodes in a similar manner.
In the episode Love Hurts, Leo is able to orb after being hit by the darklighter’s arrow. In other episodes, such as Blinded by the Whitelighter, it is stated or at least heavily implied that whitelighters cannot use their powers after being hit by a darklighter’s arrow.